1. Field of the Invention
The present invention relates to novel plant seed extract compositions that can be used for the prophylaxis, etc., of atherosclerosis. The present invention also relates to foods, feeds, and pharmaceutical compositions, which contain such a plant seed extract composition. The present invention further relates to methods of producing such a plant seed extract composition.
2. Discussion of the Background
Along with the westernization of life style in recent years, in addition to cancer, atherosclerotic diseases such as angina pectoris, cardiac infarction, cerebral infarction, and the like have become the main causes of death of Japanese people. A consensus has been generally reached that oxidation of LDL (low density lipoprotein) plays a key role in the early stages of lesion formation, and the importance of not only controlling the blood cholesterol level to a suitable range but also suppressing the production of oxidized LDL has been pointed out recently.
It has been clarified that foods, particularly a food derived from plants, contain an abundance of anti-oxidative substances, and the anti-oxidative substances contained in green tea and red wine are considered to be taken into LDL (or in the vicinity thereof) and eliminate radicals to prevent production of oxidized LDL (Fuhrman et al, Am. J. Clin. Nutr., vol. 61, pp. 549-54 (1995)). There is also an epidemiological study that concludes that a positive intake of these foods suppresses cancer and heart diseases (Renaud et al, Lancet vol. 339, pp. 1523-26 (1992)).
In the meantime, there is a report that particular components derived from particular seeds such as sesame seed lignan, grapeseed polyphenol, and the like show an anti-atherosclerotic activity with experimental animals (Kang et al, J. Nutr., vol. 129, pp. 1885-90 (1999) and Yamakoshi et al, Atherosclerosis, vol. 142, pp. 139-49 (1999)). However, the anti-atherosclerotic property of a plant seed component has been clarified at an animal test level only in a few cases, and many researches remain at a test tube level. For example, JP-A-8-337536 discloses an anti-active oxygen agent extracted from a roasted and then fermented plant seed. The technique uses a plant seed as a starting material, but has low versatility because it requires operations such as roasting, fermentation treatment and the like, and, thus, this technique is not practical. In addition, the effect of suppressing atherosclerosis is not clearly shown. Furthermore, Zhang et al (Zhang et al, Chem. Pharm. Bull., vol. 45, pp. 1910-14 (1997)) report structures of a group of compounds extracted from a safflower oil cake by distribution of various solvents, and that some of these structures have an antioxidant activity in vitro. However, it is not clear at present if such compounds having an antioxidant activity are effective for preventing atherosclerosis. In consideration of the fact that antioxidant activity in vitro is known not to be necessarily correlated to the anti-atherosclerotic activity in vivo (Fruebis et al, J. Lipid Res., vol. 38, pp. 2455-64 (1997); Fruebis et al, Atherosclerosis, vol. 117, pp. 217-24 (1995); and Munday et al, Arterioscler. Thromb. Vasc. Biol., vol. 18, pp. 114-19 (1998)), confirmation of whether or not an anti-oxidative substance in a plant seed has anti-atherosclerotic property is required at least at an experimental animal level. Moon et al. found an action of suppressing an increase of blood cholesterol in rats fed with a cholesterol-loaded feed in a powder, ethanol extract, or hot water extract of safflower seed (Moon et al, Nutr. Res., vol. 21, pp. 895-904 (2001)). However, the results of the cholesterol-loading test using the rats show evaluation of the suppression of cholesterol absorption, rather than the suppression of atherosclerosis.
On the other hand, safflower seed is known to contain a serotonin derivative known to show in vitro antioxidant activity and anti-inflammatory activity (Zhang et al., Chem. Pharm. Bull., vol. 44, pp. 874-876 (1996) and Kawashima et al., J. Interferon Cytokine Res., vol. 18, pp. 423-428 (1998)). Furthermore, some of the safflower seeds are known to contain a serotonin derivative (glycoside) (Zhang et al., Chem. Pharm. Bull., vol. 45, pp. 1910-14 (1997)). Moreover, safflower seed has been reported to contain a serotonin derivative and, as a diarrhea-inducing substance, a phenolic glycoside (2-hydroxyarctiin) (Palter. R. et al., Phytochemistry, vol. 11, pp. 2871-2874 (1972)). While 2-hydroxyarctiin has been reported to be extractable with water at pH 5, the behavior of serotonin derivatives has not been examined (Lyon. C. K. et al., J. Amer. Oil Chem. Soc., vol. 56, pp. 560-564 (1979)).